Drive mechanisms including a first wheel, a second wheel and a belt extending around the wheels are known. In such mechanisms, the belt is pulled by the first wheel (i.e., the drive wheel) when the first wheel is rotated about a first shaft (also referred to as a first axle), for example, by a motor or other power source. The belt, as it is pulled by the first wheel, in turn, pulls the second wheel which rotates about a second shaft (also referred to as a second axle).
In such mechanisms, the belt is in tension as it travels from the second wheel toward the first wheel; and the belt is in a relatively slack state as it travels from the first wheel toward the second wheel. The presence of a portion of the belt that is in a slack state results in inefficient transfer of power from the first wheel to the second wheel, and also results in the first wheel and the second wheel forming an unbalanced system, with unbalanced forces exerted on the wheels and shafts.